To learn Arcanis, OOCly you basically just need to get ARC-CT. ARC-CT has as prereqs:

CHARGEN BLD-PA

GP-ARCANIS/1

GL-PATHI/3

GL-PATHI/1 has the prereq of GL-GC/4. Thus, technically it's not all that hard.

However, this leads to questions based on our actual background. Obviously, since we go out in search of people with "the gift", and since it seems that anyone with Pathi blood tends to have it as well, the capability to learn Arcanis is as much "genetic" as intellectual.

ICly, I think it makes sense (and would be cool) if we could stipulate that in order to learn Arcanis, you need some blood of dragons. Does that mean it should be a required thing to have BLD-PA? I'm not entirely sure. I'd be willing to let that slide, but perhaps with an IC note that generally speaking, you can't just teach someone Arcanis. PCs get to "have the blood" if they want, but that is not true of the general (NPC) population. In other words, someone can't go out and start an Arcanis University in Amber, and expect that to work…

My feeling is that it isn't necessary. What play and literature I've seen implies that the talent is fairly rare, and as is, GMs aren't going to hand someone ARC-CT without some sort of RP backing it up. Adding descent from dragons as a requirement is ultimately going to limit the play option of someone with a bizarre background that precludes dragon descent (son of a god, born of a river, grown in a vat, etc), but (IMO) doesn't really seem to add any significant color.

Sure, it's rare, but why is it rare? That's where the color comes in. After a few thousand years, the blood of dragons could be found anywhere, so it's not limiting in the sense that we don't let non-Pathians have it, but it still is the hook for the ability.

If you look at the blood gifts, they do tend to limit a jack-of-all-trades aspect. Generally, you have to pay a lot extra points to get more than one line, so it's not unprecedented. If I recall, the Cibola one is completely exclusive of all others, in fact.

But to me, having the blood of dragons is a great story hook that is sitting out there to develop at some time.

However, there's a bigger question that is going to come up. Is Arcanis really something that someone can "pick up" in the time frame of the game? This will matter if an existing PC wishes to learn it outside of chargen. I know I have generally talked ICly about the years of study, and how we generally only take the young. For playability, I can see allowing advancement in almost all of the gifts, but what about the base ability of ARC-CT? It would seem to make sense for it to be a chargen-only ability, but I can see why we might let this slide too.